Re: Prop shaft material
The stainless normally used is 304 and at 1 1/4 diameter that should be well strong enough with a safety factor well over three. A more common material is tobin bronze which has about the same yield strength but is more elastic. High strength alloys include Aquamet 22, 18 and 17; Monel 400 and K500 But they're overkill for your situation. more for special situations.